Large volume test apparatuses and methods for detection of small defects

ABSTRACT

A system for detecting leaks is provided comprising an accumulator, a flow controller in communication with the accumulator, and a flow meter/sensor in communication with the accumulator, the flow controller and a UUT. The flow meter is structured to supply gas from the accumulator to the UUT and measure a flow rate of the supplied gas, the flow meter providing feedback to the flow controller representing the flow rate, and the flow controller responding to the feedback by supplying flow compensation gas to the accumulator to maintain a desired pressure in the accumulator. Methods are also provided for detecting small leaks, especially with large units under test (“UUTs”).

FIELD

The present disclosure relates generally to apparatuses and methodsdesigned to obtain precision flow measurements for use in accuratelydetecting very small leaks.

BACKGROUND

Leak detection and flow measurement capabilities are often used todetermine and quantify the presence of leaks typically on themicro-meter (nm) scale or less. Such precision is often important todetermine whether an article is suitable for certain applications, suchas for medical research, and to perform sterile products containerclosure integrity testing.

Testing for leak integrity is important in various industries because aproduct's failure may present significant hazards (e.g., to customers,patients, and healthcare professionals). In some applications, leakdetection needs to address special industry specific requirements, suchas being performed on all products and, thus, must be done without beingdestructive or corrosive to parts tested.

However, many products—such as many of those used in the medicalindustry—comprise materials that are flexible and elastic and, thus, mayexpand as gasses are used to detect leaks.

To perform such precise leak detection and flow measurements, a supplysource with sufficiently stable pressure is therefore often needed. Withconventional systems, such supply sources often incorporate a precisionconstant pressure vessel (e.g., an accumulator) that can be used tosupply gas (e.g., air, nitrogen, oxygen, hydrogen, or a tracer gas).Conventional systems typically require that the precision constantpressure vessel be ten times or more larger than the volume of theproduct being tested. This can present challenges for testing largervolume products and, in some cases, be prohibitive due to the increasedequipment, space, and cost requirements, especially in a “clean room”environment. Moreover, requiring such large volumes can increase thetime required to test large units under test (“UUTs”).

Furthermore, such systems may not be portable and, thus, may not allowfor verification that a product meets desired specifications upondelivery to a customer or to an end user at the point-of-use. In otherwords, the UUTs may not be able to be tested to ensure they were notdamages during shipping and/or storage with conventional systems.

Accordingly, systems and methods capable of precision testing of largevolume items and/or more portable systems are still needed.

SUMMARY

Thus, disclosed herein are systems and methods for detecting leaksdesigned to obtain precision flow measurements for use in accuratelydetecting very small defects in large volume UUTs.

In one embodiment, a system for detecting leaks is disclosed comprisingan accumulator, a flow controller in communication with the accumulator,and a flow sensor in communication with the accumulator, the flowcontroller and a UUT, wherein the flow sensor is structured to supplygas from the accumulator to the UUT and measure a flow rate of thesupplied gas, the flow sensor providing feedback to the flow controllerrepresenting the flow rate, and the flow controller responding to thefeedback by supplying flow compensation gas to the accumulator tomaintain a desired pressure in the accumulator. In one aspect of thisembodiment, the flow sensor is a micro-flow sensor. In another aspect,the flow sensor is an intelligent gas leak sensor (“IGLS”). In yetanother aspect, the system comprises a pressure controller incommunication with a quick fill valve, wherein the pressure controllercooperates with the quick fill valve to fill the UUT in response tofeedback from a pressure sensor of a measurement of pressure of gas inthe UUT. In a variant, this aspect further comprises a gas supplyconnected to the pressure controller. In a further variant, the pressuresensor is in communication with the quick fill valve. In another aspect,the system is a portable unit. In another aspect, the flow rate of thesupplied gas corresponds to a defect in the UUT. Still another aspectfurther comprises a gas supply in communication with the pressurecontroller. Another aspect further comprises a fill valve incommunication with the accumulator. In a variant of this aspect, thefill valve allows a gas supplied from the accumulator to bypass the flowsensor. In yet another aspect, the accumulator has an internal volumeless than about 0.5 m³.

In another embodiment, the disclosure provides a method for detectingleaks comprising supplying a UUT with a gas supplied through both apressure controller and an accumulator, supplying the UUT with a gassupplied through a flow sensor, ceasing the supplying the UUT with thegas supplied from the pressure controller, supplying the UUT only with agas supplied through the flow sensor, and determining whether a leakexists in the UUT in response to gas supplied through the flow sensor.One aspect of this embodiment further comprises supplying the UUT with agas supplied from a quick fill valve in communication with the pressurecontroller. In another aspect, the gas supplied through the flow sensoris supplied from the accumulator. In a variant of this aspect, the gassupplied from the accumulator is supplied from a flow controller to theaccumulator, the flow controller suppling gas from to the accumulator inresponse to a flow rate measured by the flow sensor. In another aspect,the gas supplied from the pressure controller is supplied from amechanical regulator. In still another aspect, the gas supplied from thepressure controller is measured by a pressure sensor. In a variant ofthis aspect, the pressure sensor provides feedback to the pressurecontroller for regulating the gas supplied from the pressure controller.In another aspect, the gas supplied from the accumulator is suppliedfrom the pressure controller to the accumulator. In a variant, the gassupplied from the accumulator is also supplied from a flow controller tothe accumulator. In another aspect of this embodiment, the flow sensoris in communication with a flow controller.

In still another embodiment, the present disclosure provides a method ofdetecting leaks using flow measurement, comprising providing gas from anaccumulator to a UUT through a micro-flow meter, wherein the accumulatorhas a volume that is equal to or smaller than a volume of the UUT, andmeasuring a leakage flow rate of the UUT using the micro-flow meter. Oneaspect of this embodiment further comprises providing compensation gasto the accumulator by a flow controller, the compensation gas beingprovided in response to a leakage flow rate of the UUT to compensate forgas discharged from the accumulator to maintain very constant pressurein the accumulator. Another aspect further comprises isolating theaccumulator during measuring a leakage flow rate to avoid pressurefluctuations of the gas provided from the accumulator.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this disclosure,and the manner of attaining them, will become more apparent and thedisclosure itself will be better understood by reference to thefollowing description of an embodiment of the disclosure taken inconjunction with the accompanying drawings, wherein:

FIG. 1 illustrates a leak detection system according to variousembodiments;

FIG. 2 illustrates method for detecting a small leak according tovarious embodiments; and

FIG. 3 illustrates a quick fill leak detection method according tovarious embodiments.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of the present disclosure, the drawings are not necessarilyto scale and certain features may be exaggerated in order to betterillustrate and explain the present disclosure. The exemplification setout herein illustrates embodiments of the disclosure, in various forms,and such exemplifications are not to be construed as limiting the scopeof the disclosure in any manner.

DETAILED DESCRIPTION

The embodiments disclosed below are not intended to be exhaustive orlimit the disclosure to the precise form disclosed in the followingdetailed description. Rather, the embodiments are chosen and describedso that others skilled in the art may utilize their teachings.

As used herein, the term small leak, may include leaks resulting fromsmall defects—which includes micro-meter defects. In order to measureair flow through small defects, a very sensitive micro-flow meter may beused. An example of such a flow meter is the Intelligent Gas Leak Sensor(“IGLS”) disclosed in in U.S. Pat. No. 5,861,546 to Sagi et al., and/orU.S. Pat. No. 6,308,556 to Sagi et al. (collectively, “the Sagipatents”), the disclosures of which are hereby expressly incorporatedherein by reference. Other micro-flow meters or sensors operating in oneor more flow regimes may also be used. Mathematical models used todetermine the presence of a leak or defect are not particularly limitedany may include any conventionally known method, including methodsdisclosed in U.S. Pat. No. 5,861,546. The measurement principle of thepresent disclosure is to measure the air flow into the UUT that replacesthe air lost through the leak, based on the mass conservation law.Hereinafter, although other suitable flow meters are contemplated by thepresent disclosure, the example of the IGLS will be described.

When measuring leakage from a UUT with a large volume, a small leak willresult in a small pressure drop, which in return will force air throughthe IGLS as described below. To assure that the air flow is indeed aresult of the leakage, a very constant pressure supply to the IGLS isdesirable. The qualifier “very constant” is intended to mean includingpressure changes that are generally smaller than the pressure changesdue to the leakage from the UUT.

As used herein, the modifier “about” used in connection with a quantityis inclusive of the stated value and has the meaning dictated by thecontext (for example, it includes at least the degree of errorassociated with the measurement of the particular quantity). When usedin the context of a range, the modifier “about” should also beconsidered as disclosing the range defined by the absolute values of thetwo endpoints. For example, the range “from about 2 to about 4” alsodiscloses the range “from 2 to 4.”

One of ordinary skill in the art will realize that the embodimentsprovided can be implemented in hardware, software, firmware, and/or acombination thereof. Various sensors, controllers, and other computerswithin the various embodiments disclosed herein may include variousprogramming codes that may be implemented in any viable programminglanguage such as C, C++, MATLAB, HTML, XTML, JAVA or any other viablehigh-level programming language, or a combination of a high-levelprogramming language and a lower level programming language. Forexample, the pressure controllers and flow controllers may contain ormay be in communication with a proportional-integral-derivativecontroller (“PID controller”) with any of the aforementioned programminglanguages.

FIG. 1 illustrates system 100 capable of testing a unit under test(“UUT”) 109 for small defects or leaks. System 100 may include anexpansion tank or accumulator 110, an intelligent gas leak sensor(“IGLS”) 120 in communication with the accumulator 110, a pressurecontroller 130 in communication with the IGLS 120, a flow controller 140in communication with the IGLS 120, and a pressure sensor 150 incommunication with the pressure controller 130.

As used herein, the term “communication” is not particularly limited andmay include mechanical, flow communication (e.g., fluid flowcommunication), electrical communication, or mixtures thereof. As usedherein, the term electrical communication is not particularly limited anmay include, for example, wired communication or wireless communication,such as radio, infrared, microwave, wireless local area network orWi-Fi, or short-wavelength ultra-high frequency radio waves, such asBluetooth. For example, system 100 is illustrated with pressurecontroller 130, flow controller 140, IGLS 120, and pressure sensor 150being configured to communicate wirelessly.

Accordingly, system 100 is not particularly limited and, in variousembodiments, system 100 may be a fixture in a building. In otherembodiments, system may be a portable unit, which may allow for testingnot only at the point-of-production (e.g., at the manufacturers site),but may also allow for product testing at another location (e.g., whenaccepting delivery of products or in the field at the point-of-use).Thus, portable devices may allow for improved certainty at receivingdocks when determining whether to accept or deny a shipment.Furthermore, portable systems may allow for improved certainty at thepoint-of-use, for example to ensure a sterile environment.

In various embodiments, pressure controller 130 and flow controller 140may be connected to a gas supply. For example, system 100 illustrates agas supply flow 102 entering gas supply inlet 101 from a gas supply,such as mechanical regulator (not shown in FIG. 1). In some embodiments,flow controller 140 may be in communication with the accumulator 110 andmay help to maintain a constant pressure or near constant pressurewithin accumulator 110, for example, when the UUT is undergoing a test.

System 100 may also comprise a quick fill valve 160, which may allow theUUT 109 to be filled directly with gas supplied through pressurecontroller 130. In some embodiments, the pressure sensor 150 may be incommunication with the quick fill valve 160. System 100 as shown alsoincludes a test valve 170 between IGLS 120 and UUT 109.

System 100 may also comprise an isolation valve 190, which may allow orrestrict gas supply from the pressure controller 130 to the accumulator110. Thus, when in the open position, isolation valve 190 will allow gassupplied through the pressure controller 130 to enter the accumulator110. Also, in various embodiments, flow controller 140 may also supplygas to accumulator 110.

System 100 may also comprise a fill/by-pass valve 180 that may allow gassupplied from the accumulator 110 to bypass the IGLS 120 and enter intothe UUT 109. Thus, fill/by-pass valve 180 may be connected to theaccumulator 110.

Furthermore, the various valves and controllers are not particularlylimited and may include mechanical valves, mechanical sensors,electrical valves, electrical sensors, or combinations thereof.

Pressure sensor 150 may be positioned near the UUT 109 and may monitorthe pressure of the UUT. Thus, in various embodiments, when the UUT 109is being filled quickly, filled under a normal flow rate, filled slowly,or being tested, the pressure sensor 150 may help to monitor, control,and/or ensure the pressure of the supply to the UUT 109 remains within adesired pressure range.

Thus, system 100 may allow for the UUT 109 to be filled quickly withoutusing gas supplied from the accumulator 110. By filling a significantportion of the UUT 109 without using gas supplied through theaccumulator 110 before testing, the amount of gas supplied through theaccumulator 110 may be reduced and, thus, reduce the pressurefluctuations within accumulator 110, for example, from turbulentairflow.

Reducing the pressure fluctuations within accumulator 110 may allow forsmaller and more compact systems than conventional systems. This may notonly allow for improvements such as reduction of space needed for suchsystems and material cost savings, but may also allow for such systemsto fill much larger UUTs without increasing the size of the accumulator110. Thus, while some conventional systems require an accumulator 110ten or more times the size of the unit under test, the systems withinthe scope of this disclosure may allow for accumulators with reducedinternal volumes. Thus, in some embodiments, the accumulator 110 mayhave an internal volume less than twice the volume of UUT 109, and incertain embodiments, a fraction of the UUT volume. In one example, ifthe UUT volume is 200 liters, then the accumulator volume may be lessthan 50% of that volume.

Thus, the various systems disclosed herein allow for improved methodsfor detecting small leaks in apparatuses with large volumes (e.g.,larger than 50 liters, such as volumes between about 50 liters and 3,500liters). Furthermore, it should be noted that while the systems andmethods disclosed herein may be used to test apparatuses having largevolumes, they may also be used with apparatuses with smaller volumes.

Moreover, the IGLS 120 may measure the gas that passes from theaccumulator 110 into the UUT 109. By measuring the gas supplied, theIGLS 120 may monitor and/or control the pressure controller 130 and/orthe flow controller 140 to provide flow into accumulator 110proportional to the flow exiting from accumulator 110 into the IGLS 120,resulting from a defect or leak in the UUT 109. In various embodiments,the flow commanded to flow controller 140 may be equal to, smaller than,or greater than the flow rate measured by the IGLS.

When constant pressure at the accumulator 110 is maintained, the IGLS120 may be able to measure the flow rate into the UUT 109 and, thus, maytest for a small leak. Thus, the gas that is supplied through the IGLS120 may be supplied from the accumulator 110. Moreover, the gas suppliedfrom the accumulator 110 may be supplied from the flow controller 140 tothe accumulator 110.

Thus, in various embodiments, the accumulator 110 may be isolated toprevent pressure ripples from the supply from adversely affecting thepressure in the accumulator 110 and, thus, through the IGLS 120.

In one test sequence, an initial quick fill process is executed to bringthe UUT 109 to a nearly filled state rapidly. In this step, isolatorvalve 190, fill/by-pass valve 180 and test valve 170 are closed. Supplygas is provided through pressure controller 130 and quick fill valve 160to the UUT 109. Pressure sensor 150 indicates to pressure controller 130when UUT 109 approaches a filled state. Next, a fill process isexecuted, wherein all of the valves are opened such that gas flows toUUT 109 from pressure controller 130 through quick fill valve 160 andfrom pressure controller 130 through accumulator 110 and IGLS 120.During this step, flow controller 140 does not provide flow compensationto accumulator 110.

When pressure sensor 150 indicates that UUT 109 is filled with gas,system 100 executes a stabilization process wherein all valves areclosed except test valve 170 and flow controller 140 provides flowcompensation to accumulator 110. In this manner, IGLS 120 measures flowto UUT 109 as UUT 109 stabilizes and provides the flow information toflow controller 140. Flow controller 140 uses this feedback to provide asimilar flow as compensation to accumulator 110. When the flow throughIGLS 120 stabilizes, the system 100 executes a measurement of the flowrate through IGLS 120 which represents the existence and extent of adefect or leak in UUT 109 in a manner disclosed in the Sagi patents.

FIG. 2 illustrates method 200 for testing a UUT for a small leak. Method200 may include supplying a UUT with a gas supplied through both apressure controller and an accumulator (step 210). The gas supplied tothe pressure controller is not particularly limited and may be suppliedfrom a mechanical regulator.

Method 200 also may include supplying the UUT with a gas suppliedthrough an intelligent gas leak sensor (“IGLS”) (step 220), ceasingsupplying the UUT with the gas supplied from the pressure controller(step 230), and supplying the unit under test only with a gas suppliedthrough the IGLS (step 240). In various embodiments, gas supplied to theIGLS may be supplied gas that passes through an accumulator.

The gas supplied to the accumulator is not particularly limited and maybe supplied from the pressure controller to the accumulator and/or maybe supplied from a flow controller to the accumulator. In oneembodiment, a flow controller supplies gas to the accumulator inresponse to feedback from the IGLS indicating the flow rate of gas beingsupplied to the UUT.

Method 200 also includes determining whether a leak exists in responseto the gas supplied through the IGLS (step 250). In various embodiments,the IGLS may be able to determine the presence of a leak based on flowthrough the IGLS to the UUT.

The order of the steps disclosed herein are not particularly limitedand, thus, may vary from those exemplified in FIGS. 2 and 3. Forexample, with continued reference to FIG. 2, the supplying of the UUTwith a gas supplied through an IGLS (step 220) may come after thesupplying of the UUT with the gas supplied through the pressurecontroller and the accumulator has ceased (step 230).

Method 300 exemplified in FIG. 3 may also include the additional step ofsupplying the UUT with gas supplied from a quick fill valve incommunication with the pressure controller (step 360). According tovarious embodiments, filling the UUT with a gas supplied from a quickfill valve in communication with the pressure controller may allow forthe system to fill the UUT bypassing the accumulator, such asaccumulator 110 exemplified in FIG. 1.

This may help to reduce the turbulence in accumulator 110, and may allowthe test time to be reduced and/or the size of the accumulator to bereduced. As described above, the gas supplied from the pressurecontroller—for example during a quick fill—may be measured by thepressure sensor. Also, the pressure sensor may assist in regulating thepressure controller and, thus, may ensure that the supplying of gas tothe UUT does not damage the UUT. In some methods, using the quick valvemay allow the UUT to arrive near the test pressure rapidly and reducethe required test time.

While this disclosure has been described as having exemplary designs,the present disclosure may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains.

It should be noted that many alternative or additional functionalrelationships or physical connections may be present in a practicalsystem. However, the benefits, advantages, solutions to problems, andany elements that may cause any benefit, advantage, or solution to occuror become more pronounced are not to be construed as critical, required,or essential features or elements. The scope is accordingly to belimited by nothing other than the appended claims, in which reference toan element in the singular is not intended to mean “one and only one”unless explicitly so stated, but rather “one or more.”

In the detailed description herein, references to “one embodiment,” “anembodiment,” “an example embodiment,” etc., indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art with the benefit of the presentdisclosure to affect such feature, structure, or characteristic inconnection with other embodiments whether or not explicitly described.After reading the description, it will be apparent to one skilled in therelevant art(s) how to implement the disclosure in alternativeembodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises,”“comprising,” or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A system for detecting leaks comprising: anaccumulator; a flow controller in communication with the accumulator;and a flow sensor in communication with the accumulator, the flowcontroller and a UUT; wherein the flow sensor is structured to supplygas from the accumulator to the UUT and measure a flow rate of thesupplied gas, the flow sensor providing feedback to the flow controllerrepresenting the flow rate, and the flow controller responding to thefeedback by supplying flow compensation gas to the accumulator tomaintain a desired pressure in the accumulator.
 2. The system of claim1, wherein the flow sensor is a micro-flow sensor.
 3. The system ofclaim 1, wherein the flow sensor is an intelligent gas leak sensor(“IGLS”).
 4. The system of claim 1 further comprising a pressurecontroller in communication with a quick fill valve, wherein thepressure controller cooperates with the quick fill valve to fill the UUTin response to feedback from a pressure sensor of a measurement ofpressure of gas in the UUT.
 5. The system of claim 4 further comprisinga gas supply connected to the pressure controller.
 6. The system ofclaim 4, wherein the pressure sensor is in electrical communication withthe pressure controller.
 7. The system of claim 1, wherein the system isa portable unit.
 8. The system of claim 1, wherein the flow rate of thesupplied gas corresponds to a defect in the UUT.
 9. The system of claim1 further comprising a gas supply in communication with a pressurecontroller.
 10. The system of claim 1 further comprising a fill valve incommunication with the accumulator.
 11. The system of claim 10, whereinthe fill valve allows a gas supplied from the accumulator to bypass theflow sensor.
 12. The system of claim 1, wherein the accumulator has aninternal volume less than about 0.5 m³.
 13. A method for detecting leakscomprising: supplying a UUT with a gas supplied through both a pressurecontroller and an accumulator; supplying the UUT with a gas suppliedthrough a flow sensor; ceasing the supplying the UUT with the gassupplied from the pressure controller; supplying the UUT only with a gassupplied through the flow sensor; and determining whether a leak existsin the UUT in response to gas supplied through the flow sensor.
 14. Themethod according to claim 13 further comprising supplying the UUT with agas supplied from a quick fill valve in communication with the pressurecontroller.
 15. The method according to claim 13, wherein the gassupplied through the flow sensor is supplied from the accumulator. 16.The method according to claim 15, wherein the gas supplied from theaccumulator is supplied from a flow controller to the accumulator, theflow controller supplying gas from to the accumulator in response to aflow rate measured by the flow sensor.
 17. The method according to claim13, wherein the gas supplied from the pressure controller is suppliedfrom a mechanical regulator.
 18. The method according to claim 13,wherein the gas supplied from the pressure controller is measured by apressure sensor.
 19. The method according to claim 18 wherein thepressure sensor provides feedback to the pressure controller forregulating the gas supplied from the pressure controller.
 20. The methodaccording to claim 13, wherein the gas supplied from the accumulator issupplied from the pressure controller to the accumulator.
 21. The methodaccording to claim 20, wherein the gas supplied from the accumulator isalso supplied from a flow controller to the accumulator.
 22. The methodaccording to claim 13, wherein the flow sensor is in communication witha flow controller.
 23. A method of detecting leaks using flowmeasurement, comprising: providing gas from an accumulator to a UUTthrough a micro-flow meter, wherein the accumulator has a volume that isequal to or smaller than a volume of the UUT; measuring a leakage flowrate of the UUT using the micro-flow meter; and isolating theaccumulator during measuring a leakage flow rate to avoid pressurefluctuations of the gas provided from the accumulator.
 24. The methodaccording to claim 23, further comprising providing compensation gas tothe accumulator by a flow controller, the compensation gas beingprovided in response to a leakage flow rate of the UUT to compensate forgas discharged from the accumulator to maintain very constant pressurein the accumulator.